Guiding Ar⁸⁺ ions through a biconvex cylindrical glass channel

To develop a new ion-beam control technique, we examined the guiding effect of highly charged ions using a glass channel. A 20 keV Ar 8+ ion beam was injected into a biconvex cylindrical glass channel (BC-CGC), comprising two cylindrical convex lenses facing each other with a 1 mm gap. Subsequently, the time evolution of the charge state, kinetic energy, deflection angle and count rate of the transmitted ions was evaluated using a two-dimensional position-sensitive detector. When a pulsed ion beam was injected into the BC-CGC at a 3° tilt relative to the beam axis, mean charge state of the transmitted ions decreased by less than one. However, the kinetic energy remained at its initial value and the absolute deflection angle increased exponentially with a time constant of 8.0 × 10 2 s. In another experiment using a direct current beam with a fluence rate 11 times greater than that of the pulsed beam, the absolute deflection angle of the transmitted ions exhibited a similar exponential increase, with a time constant of 6.5 × 10 2 s. A comparable exponential time dependence was observed for the count rate of the transmitted ions but with a shorter time constant of 37 s.